21512516 has 12 divisors (see below), whose sum is σ = 38163132. Its totient is φ = 10608768.

The previous prime is 21512509. The next prime is 21512527. The reversal of 21512516 is 61521512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 16240900 + 5271616 = 4030^2 + 2296^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21512491 and 21512500.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36545 + ... + 37128.

It is an arithmetic number, because the mean of its divisors is an integer number (3180261).

Almost surely, 2^21512516 is an apocalyptic number.

It is an amenable number.

21512516 is a deficient number, since it is larger than the sum of its proper divisors (16650616).

21512516 is a wasteful number, since it uses less digits than its factorization.

21512516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73750 (or 73748 counting only the distinct ones).

The product of its digits is 600, while the sum is 23.

The square root of 21512516 is about 4638.1586863754. The cubic root of 21512516 is about 278.1188353808.

The spelling of 21512516 in words is "twenty-one million, five hundred twelve thousand, five hundred sixteen".